Heckler & Koch MP5 sub-machine guns can be found in various mods. But often the package bundle is not enough. 
In this mod you can use 4 basic types of models and several modifications. 
Hopefully, that in future, I will make more of models and different modifications.

Game Location:
SMG can be found in one of the Nellis Air Force Base buildings (or barracks).
Or you can just enter the console code.

Carbines can be set to semi, 3 round burst, full automatic fire if Installed New Vegas Script Extender and Select Fire Script.
Press the 'M' key to switch fire modes.
SelectFire.esm is in the mod .zip file and must be installed in the game directory, 
If you have not used it previously with other mods.

Console code:

MP5Ax 9mm SMG			= xx000dbc
MP5SD 9mm SMG			= xx00109b
MP5Ax 10mm Auto SMG		= xx00109d
MP5SD 10mm Auto SMG		= xx001c15

MP5 Silencer 			= xx00137c 
MP5 EOTech 3X Magnifier 	= xx00137a
MP5 ACOG scope			= xx001379 
MP5 fixed buttstock		= xx00137b 

Requirements:
New Vegas Mod Manager: 
http://www.newvegasnexus.com/downloads/file.php?id=36901
Select Fire Script:
http://www.newvegasnexus.com/downloads/file.php?id=40242
New Vegas Script Extender:
http://nvse.silverlock.org/

Installation:
Delete files and folders associated with the previous version of this mod, 
especially the old .esp file. 
Do not use both the two .esp files of different versions.
Extract the new files to a temporary location.
Place the files in your Fallout NV Data folder (ie ..\Fallout New Vegas\Data) and place a checkmark next to the .esp file.

Uninstall:
Delete the files/folders associated with the mod.

Issues or Bugs:
Specify them to me and I will correct them so quickly as soon as I can.

Credits:
MP5 model - Twinkie Masta
MP5 texture - Stoke 
ACOG model - TheLama
ACOG texture - El Maestro de Graffiti
Reflex sight model - Snark Skin
Reflex sight texture - Snark Skin
Silencer textures - SureShot
3x Magnifier model - Twinke Masta
3x Magnifier textures - WangChung

Sorry if I forgot someone.

And special thanks to  Kerededyh, Dread Wolf and Corejob for their Select Fire Script.
http://www.newvegasnexus.com/downloads/file.php?id=40242

License/Legal:
You can't use the plugin resources (models, textures, etc) without my permission.